Bluebell Railway General Discussion

In my old day job, I was certified to be able to work in 3rd rail areas but thankfully I never had to actually be in a 3rd rail area.
Unlike OHLE which I would be likely to work around day in day out.

I seem to recall one difference between 3rd rail and Overhead.
One sticks you to the rail and does not let go while the other throws you off.
Which one might let you live?

Maybe it's the perceived risk and the greater degree of separation from the juice.
You can come in contact with 3rd rail through a trailing bit of clothing or equipment, whereas with OHLE it's up in the air, out of the way and even on a platform you should have more than 9ft clearance. Yes there are traction cables and bonding at ground level but not to the same risk.

 

I think there are quite a few Bluebell staff who have their main job working on the big railway who are against even a dummy third rail at HK for exactly that reason.

Tom

 

Many moons ago, I was in the leading carriage of a 4VEP, on the Reading-Waterloo line, which picked up what looked like a bog chain, on the collector equipment, around Sunningdale. Said chain sparked intermittently until the train arrived at Twickenham, where a chap in BR uniform attempted to dislodge it with a broom handle. There followed a very loud 'pop', the chap's bald pate went from skin coloured to blackened and peeling, literally 'in a flash' and there was a very marked and dreadful singing smell. Mercifully, beyond being badly shaken, he was OK as our driver dismounted to lead him onto the platform and assistance. It's not a sight I'd care to see again.

 

My favourite is the Northern Line being brought to a halt, by a fancy dress wizard's hat shorting out the traction current

 

I would be far more concerned not to get close to 25kV than 750V. Obviously it is best to avoid both!

 

The Driver should have first obtained an isolation of the traction current, secondly apply a Short circuit bar to the conductor rail and then use a shoe paddle to lift the shoe clear of the conductor rail.
I take it that we are not going to restart the debate on electrifying East Grinstead to Ardingly again!

 

I have posted in this vein before, I seem to recall, but in simple terms - Read your LRO and TWAO. I'd be surprised if any electrification is permitted.
Pat

 

Indeed, though the guy who nearly got fried was identifiably station staff, who's job I'm guessing, it wasn't to attempt to remove the chain in the first place. It was a decidedly sobering sight, which rather underlines why overly close proximity to conductor rails isn't a great idea.

Down here, Volk's Electric Railway runs on a nominal 110vdc (with unboarded off-centre conductor rail), which voltage drops well below 100 at times. This is lower than was utilised during Magnus Volk's lifetime. Even now, I'd not care to experience a jolt. I can't recall any serious incidents imvolving people over the 35 years I've lived here but have seen mention of two historic fatalities, both young children who'd just come out of the sea (the like's been operating since 1883), although the line's safety record for dogs hasn't been as good, over the years.

On balance, I suspect not too many would be in favour of a live juice rail on any heritage line.

 

I think lots of people seem to want to reopen that debate, but not any of the people who are actually involved in operating the line!

Tom

 

I think it’s safe to say that third rail electrification is never going to happen on any heritage line.

However the developments in battery technology are interesting, as are the Essex group’s plans for the ex IOW class 483s. Hopefully EMUs might be able to operate on heritage lines in future.

 

Just to close off a few points (if Al will let me)

Re only having the juice rail live when a train is in section - the 'safe' third rail as used on some French tram systems is an electric rail between the running lines even on street sections shared with pedestrians. This is allowed because the rail is energised in such small sections (and vehicle location is so precise) that the rail is only ever live underneath the centre of the vehicle itself and will not be live anywhere else. The system is popular as it avoids unsightly overhead cables. It is questionable whether the concept could ever be transferred to heritage railway use without very substantial re-engineering. It may be possible to reduce risk substantially by having platform area third rail only live for as short a time as possible, but surely is simpler to just install batteries on the trains themselves.

Hopefully that is this idea put to bed now

 

I'm curious to know the physics of what happened there, if you know. (I ask as I'm an electrical engineer, but in low-voltage digital, none in high-voltage stuff.) I assume that somehow a circuit was formed through (or across the surface of) the broom handle, and the poor gentleman's body, to ground? If so, I guess the broom handle wasn't as good an insulator as he assumed!

Noel

 

H&S advisor hat on.

Is the third rail necessary- does it pose an unnecessary risk to staff & visitors and could it encourage complacency if is there but not live...

Answer yes.

So why on earth would you bother?

Chris

 

Nobody with the ability to actually do it ever would. Although that's what they said about Brexit.

Simon

 

I don't believe a short piece of dummy third rail on a heritage line would result in any increase in complacency elsewhere where third rail is in use 'for real'.

 

I spent time in the local telephone Exchange in the 1970s and the training message was " volts, jolt, mills, kill" meaning that one shouldn't overlook that a relatively low voltage DC source can easily melt a screwdriver, wedding ring or wrist watch for the unfortunate technician should they short a bus-bar - even though the source at the TE was 50v dc.

On the other hand, a static shock from a nylon carpet or the like would involve many 000s of volts if only at minute current. I seem to recall that the training I received told us that it took only 40-60 mA across your chest to stop your heart!

600-700 vdc and 25Kv ac are not to be compared in terms of which would kill you worse or fastest!

 

An HSE Inspector giving a talk stated that the lowest voltage known to have killed someone was 1½ volts. The person concerned had a pacemaker fitted and it stopped that. How true, I cannot say.

 

I don't think there will ever be 3rd rail electrification on a heritage railway and also any dummy or replica other than a very temporary installation is a no go as well.
I had a DC lines PTS when I worked for BR (yes it was quite a while ago) and also held a DC and AC lines PTS for when some choochoo went to London Town for a cheeky film job.
Our instructor for my recent one said 80% of people survive contact with a 3rd rail, 80% of people die if they touch the OHLE. IIRC the current supplied can be in the 8000 A region in 3rd rail territory. I stand to be corrected. As I said it was a long time ago.
Running tender first watching the wire get very close to the cab was very unnerving. Some bridges are quite low.
I had to wind points at Keymer Jn a few times, 319s whizzing past your ear at 90 and not a lot of room at the junction.
It was always in the rain because that's what made the track circuits fail. I really don't miss all of that.

 

The energy transferred is the killer. I've had quite a few jolts from devices such as a Van Der Graaf generator, probably about 120kV but I'm still here as the current was very low. On the other hand I have seen a photo of a fox strolling along the 3rd rail. OK for the fox as the 750V was insufficient to produce a significant current across his dry, hard pads.